Gneiss metamorphic rock

Gneiss

Metamorphic rock that forms under intense pressure and high temperature and that is made of quartz, feldspar, amphibole and mica. Gneiss represents the highest grade of metamorphic rock, which is characterized by alternating bands of dark and light-colored minerals, foliation (i.e., parallel alignment of planar minerals) and tight folding. This rock type is common at mid to deep levels of continental crust.

Geothermal Glossary

Word of the Week – Magnetotelluric (MT)  Geophysical Method

Word of the Week – Magnetotelluric (MT) Geophysical Method

Magnetotelluric (MT) Geophysical Method Makes use of naturally occurring electromagnetic waves to image the resistivity structure of the subsurface. The results can reveal the locations of hot geothermal fluids, blankets of clay alteration, and highly saline water. MT...

Word of the Week – Microseismicity

Word of the Week – Microseismicity

Microseismicity Tiny earthquakes that result from slip or shear along a fracture caused by an uneven distribution of stress. The displacements are very small scale and unfelt at the surface. They can only be detected with sensitive equipment such as geophones and...

Word of the Week – Mineral Geothermometer

Word of the Week – Mineral Geothermometer

Mineral Geothermometer A secondary mineral phase whose stability is defined by a lower and sometimes an upper temperature threshold. Common mineral geothermometers comprise clays, zeolites and epidote, with crystal structures that contain a hydroxyl (OH-) or water...

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